Low octane C5
Thread Starter
Burning Brakes
Joined: Jun 2003
Posts: 922
Likes: 1
From: Lexington KY
Low octane C5
Has anyone converted or detuned the C5 for use with low octane fuel. With gas prices so high I would think some daily drivers might want to sacrifice some horses for cheap gas. Thanks and flame suit donned. 
Le Mans Master
Joined: Jun 2004
Posts: 6,269
Likes: 50
From: Dallas Texas
St. Jude Donor '06-'07-'09-'10
Originally Posted by chasswartz
The c5 will run on 87 octane, the manuel says it will have less power, but i have not noticed. I have a 03 with 70,000 miles, most of them on 87 octane. It will not hurt your car.
the C5 detunes it's self when you use 87. The computer retards the spark advance. 
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I run mid premium all of the time! 
It works fine even in my Z06. If I need to run her hard at the track i fill it up with 93. If your just commuting and not running it hard, mid premimul will work JUST FINE! I have never tried 87. If I were in a pinch, I wouldnt have any issues doing it. Just remember that you cant play and I would add a bottle of chevron techron fuel system cleaner at every other tank full.
BC
It works fine even in my Z06. If I need to run her hard at the track i fill it up with 93. If your just commuting and not running it hard, mid premimul will work JUST FINE! I have never tried 87. If I were in a pinch, I wouldnt have any issues doing it. Just remember that you cant play and I would add a bottle of chevron techron fuel system cleaner at every other tank full.BC
Instructor
Joined: Jun 2005
Posts: 214
Likes: 0
From: Wilson NC
Around here the high test is usually 20 cents more than the regular, so for 20 gallons that's $4 more, or a little more than an extra gallon. Either don't buy a pack of smokes or use 1 less gallon of gas and you have made the difference
Melting Slicks
Joined: Dec 2003
Posts: 2,857
Likes: 2
From: pawleys island sc
bozo4onion, the answer to YOUR QUESTION is yes. The car is set-up to run on 87 octane, but with lowered performance for those 165 mph runs you usually do on your way to work. There IS a reason GM engineers like Evil Twin put that program in the car originally - to allow the use of lower octane without causeing damage to the car, should the owner and payer of the car want to do so. .
Drifting
Joined: Jun 2002
Posts: 1,847
Likes: 1
From: Iowa
Cruise-In IV Veteran
Cruise-In V Veteran
Originally Posted by sxe60
the C5 detunes it's self when you use 87. The computer retards the spark advance. That's funny. My stock '04 coupe pings on 91 octane. It'd probably go NUTS on 87 octane.
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Pro
Joined: Jun 2004
Posts: 618
Likes: 0
From: Houston TX
Unless the Corvette is different, the engine does NOT have any way of knowing what fuel you are putting into the tank. As such, it can't auto-switch to a set of different "healthy" maps. What happens is that a knock-sensor can detect detonation and retard the timing accordingly to protect the engine from damage. But 1) knock-sensors in most cars are not that sensitive since its hard for them to filter out all the other "noise" 2) thats a reactive system. You're unlikely to grenade your system, and probably won't be concerned under light throttle and normal weather conditions... but still... its a Vette. If you're just going to work, you could get yourself an extra cheap bike (few don't break 40mpg) or pickup a little 1990 CRX HF which is rated 49 mpg / 52 mpg (set you back less than $2K for a gem... and tires and such are almost free). 
